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Visionary technology figure Elon Musk has been the public for months about possible threats posed by artificial intelligence. But now he has a timeline.

Musk, the African-born CEO of Tesla Motors and SpaceX, wrote that “the of something seriously dangerous happening is in the five year time . 10 years at most.”

Musk penned this comment at the bottom of an essay written by virtual pioneer Jaron Lanier called “The Myth of A.I.” The essay appeared in the publication Edge.org last and was followed by comments from such technology notables as George Dyson, Diamandis, and Kevin Kelly.

While Musk’s comment was deleted, it was picked up by sites such as Mashable and Reddit, which preserved it for a larger audience. According to these sites, Musk zeroed in on companies such as DeepMind, a British artificial intelligence company that Musk once invested in before it was purchased by Google.

“The of progress in artificial intelligence (I’m not referring to narrow AI) is incredibly ,” Musk’s piece read. “Unless you have direct to groups like DeepMind, you have no idea how -it is growing at a pace close to exponential.”

Musk mentioned that AI companies “ the ” and were working to ameliorate any negative intelligences “from escaping into the Internet.”

While Musk had sent his comment privately to Edge.org by email, it was published by a site editor before it was taken down. A Musk spokesperson has said that Musk will write a longer piece outlining his thoughts on the dangers of artificial intelligence, presumably to be published on the same website.

Previously, Musk has compared AI to “summoning the demon,” nuclear war, and the “Terminator” series.